Described herein are a package for the active medical devices and methods of manufacture and/or use not found in the literature or practiced in the field. The literature is of interest for its teachings of the knowledge of skilled artisans at the time of this invention of the package for the active medical device and method of assembly and testing thereof.
Disposable medical devices are sold in groups of like size and type which are typically carried in an over carton in a dozen or more individually packaged, identical devices. A package can be removed from the over carton and opened to obtain a single disposable device. Individual packaging maintains a sterile barrier for each disposable medical device. Consequently, the package for each should be inexpensive, easy to open without contamination of the product and structurally adequate to protect the sterility of the product prior to use.
Commonly used packaging for disposable medical devices includes two components; a flat top or cover with printed product information as, for example, product size, type, name of manufacturer, instructions and the like. The top or cover is usually a thin sheet of extrusion coated paper having a polyethylene layer and a heat sealable lacquer layer. The paper is called Tyvek paper and the polyethylene is added for tear resistance.
The other or second component of the often used package is a drawn semi rigid tub which has a recess for receiving the product and a flange for supporting the top or cover. The tub is thermal formed from semi rigid polymer sheet which is heated and drawn such that the depth of the recess is no more than one and one-half times the width. Products which are wider than they are deep have to be packed sideways, or the package has to be drawn less than required for efficient use of the drawn polystyrene material. Typically, the flange is the thickest part of the formed tub in that it is not drawn and the corners of the recess are the thinnest area because they are stretched the most. A ratio of flange thickness to corner thickness of six to one is about the maximum amount of thinning that can be accomplished with an economical starting thickness for the polymer sheet. The flange protects the device and provides support during opening.
The cover and tub flange are heat sealed to securely enclose the product within the recess of the tub, but a portion along an edge is usually left unsealed in order to provide an area where the top can be peeled from the flange. In particular, the unsealed portion of the edge of the top can be fanned away from the edge of the flange and then grasped and peeled away from the heat sealed areas about the rest of the flange. The product remaining within the recess is supported thereby during peeling. After removal of the top or cover, the product can be accessed without having violated the sterile field of the product, but the use of gloved hands is necessary to maintain sterility. Since the product and package are typically sterilized after assembly but before use, the package has to remain a barrier to microbes and the like until the described opening procedure is performed.
Active medical device may include optical fibers or fiber optic chemical sensors used in vivo as probes; such devices must be sensitive to slight changes in gas or ion concentrations. U.S. Pat. No. 4,200,110 has a fiber optic probe with an ion permeable membrane enclosure about the distal ends of a pair of fiber optics. Change in color of a pH sensitive dye is detected. U.S. Patent No. Re. 31,879 has a method for measuring concentration of an analyte in a sample that changes color and/or the intensity of light emitted from a fluorescent indicator attached to the fiber. U.S. Pat. No. 5,047,208 has an optical sensor for blood gas measurement with a pH sensitive absorption dye between the end of the fiber and a mirror. The mirror is located by a tube which carries a mirror spaced from and coaxially aligned with the fiber so the dye can be in the space. These and other patents are typical of the microscopic constructions required for in vivo blood analysis and the manner in which structures have been made.
Blood gas sensors are typically packaged in a vessel filled with solution and then sealed in a sterility protecting package as described. The solution maintains the chemicals of the sensor fresh and ready to be used. Optic and electrical signals may be transmitted and returned through miniature conductors pass through a lumen of the blood sensor catheter during use in vivo. The ability to access those miniature conductors before delivery to verify that the sensors are viable and may be used reliably is important to the manner in which active medical devices are handled in their distribution and ultimate application.